Strings and Things: All Tangled up in the Quest for the Ultimate Theory
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For more than half a century, cosmologists covering the globe have wrestled with questions about the beginning of the universe. There are two foundational pillars upon which modern physics rest. The problem, however, is they are polar opposites. Einsteins theory of general relativity provides the theoretical framework for understanding the universe on the largest of scales. Quantum mechanics, however, provides a theoretical framework for understanding on the smallest of scales. After years of research, physicists have proven points of interest from both sides–but because of their incompatibility, they both cannot be right. This leads to other discussions pertaining to the “Big Bang theory,” “Superstring theory,” and the “Cyclic Universe theory,” all of which are growing increasingly popular as the scientific world continues to progress into the twenty-first century. It could take life-times to prove or disprove each current model, but one thing is certain: the quest for the ultimate theory will continue for long after the deaths of todays scientists, and will thrive in the hearts and minds of tomorrows common people.
In 1951, Pope Pius XII approved the Big Bang theory, which was an outrageous step towards the future for the Catholic Church. For hundreds of years, scientists like Galileo were put under house arrest for suggesting the Earth orbits the sun, and the pope was accepting a controversial theory to explain the beginning of the world! The points he found appealing, though, were the ones that worried cosmologists: in the Big Bang theory, the universe had a beginning and time and space leaped out of utter nothingness–confirming the first few sentences of Genesis. While a little precautious, astrophysicists followed the popes lead as evidence for the Big Bang grew too powerful to ignore (Lemonick 36).
The basis of the Big Bang theory is this: 13.7 billion years ago, 100 billion galaxies and 100 billion stars, stretching out beyond 10 million light-years, were once squashed into a space smaller than a single electron. That is all well and good, but the question of what made it go “bang” still puzzles scientists. The theory requires time and space to have a beginning, but the more cosmologists try to explain the beginning, the messier their model becomes. The original Big Bang model was simple: a hot dense ball of energy burst outwards, congealed into matter, and continues to expand today. Conjuring up these new, unknown energy fields goes against both common sense and cherished scientific doctrines. These questions will continue to flabbergast scientists until the real beginning of time can be marked (Lemonick 38).
Cosmic expansion was discovered in 1929 by Edwin Hubble, although its sources have not been confirmed. In the 1980s, astrophysicists, tiring of the Big Bang, turned towards an elaboration of it, called inflation. The inflation theory postulates that in the first hundred-millionth of a billionth of a billionth of a billionth of a second of its life, the universe expanded as though it were turbocharged, swelling faster than the speed of light, before settling down to a more sedate speed of growth (Lemonick 38). Alan Guth says, “Inflationary theory itself is a twist on the conventional Big Bang theoryThe conventional Big Bang theory, without inflation, was really only a theory of the aftermath of the Bang. It started with all of the matter in the universe already in place, already undergoing rapid expansion, already incredibly hot. There was no explanation of how it got that way. Inflation is an attempt to answer that question, to say what “banged,” and what drove the universe into this period of enormous expansion. Inflationexplains not only what caused the universe to expand, but also the origin of essentially all the matter in the universe at the same time” (Guth 1). Inflation is not quite a theory of the ultimate beginning, but instead a theory of evolution starting from almost nothing.
The principle idea behind inflation is that a repulsive form of gravity caused the universe to expand into its uniform, isotropic, and homogeneous existence. That is, it looks the same everywhere, in all directions. The difficult matter to explain is how the universe came to be that smooth. The conventional Big Bang theory never had a true explanation for the levelness, instead, it was just assumed from the start. In the context of this theory, it would be necessary for energy and information to be transferred at more than 100 times the speed of light across the universe. In the inflationary model, this problem goes away entirely, because it proposes a period of accelerated expansion while the repulsive gravity is occurring. In short, the theory explains that it is uniform because it came from something that had time to be uniform, and was then stretched out by this process of inflation (Guth 2).
Yet another elaboration upon the Big Bang theory is the Cyclic Universe model, where the universe is endless. More specifically, the universe goes through cycles of evolution from hot to cold, dense to under-dense, hot radiation to the structure we see today, and eventually an empty universe. A sequence of events takes place, and the cycle begins again. This incredible proposition eradicates the need for a definite beginning of time, because time is infinite–going backwards forever into the past, and proceeding eternally into the future (Steinhardt 1).
This cyclic notion has been a recurring theme in western thought. Edgar Allan Poe, Friedrich Nietzsche, and Albert Einstein were all captivated by this eternal simplicity. Paul Steinhardt, modern advocate of the cyclic model, explains the appeal: “If you have a universe with a beginning, you have the challenge of explaining why it began and the conditions under which it began. If you have a universe, which is cyclic, it is eternal, so you dont have to explain the beginning” (Steinhardt 2).
There are various technical problems, however, with trying to incorporate a cyclic model into modern cosmology. Every time the universe contracts, into what is known as a big crunch, the density and temperature of this universe rises to an infinite value, therefore it is not known if the usual laws of physics can be applied. Second, every cycle in which the universe expands and contracts, more entropy (a measure of disorder within a system) is created through natural thermodynamic processes. So at each new cycle, the entropy density is higher than the previous, increasing the length of the cycle. Traveling backwards in time, the cycles decrease in size, until after a finite time, they contract to zero duration. Therefore, the problem of avoiding a beginning has not been solved, just merely pushed back a couple of cycles (Steinhardt 2).
Paul Steinhardt has